The MakerBot electronics ecosystem is comprised of 3 parts: your computer, the MakerBot’s motherboard, and the extruder controller board. Your computer talks to the motherboard via a USB<->TTL interface (such as this FTDI cable from SparkFun). In turn, the motherboard communicates with the extruder using another serial protocol, RS-485, over an ethernet cable. Finally, the extruder triggers the camera via the custom cable I made in the previous post.

To send a message to the extruder - in this case, to activate or deactivate the camera - we must create a packet for the motherboard. The HOST_CMD_TOOL_QUERY code allows us to send the motherboard a packet which it will then pass along to the extruder controller.

That’s great, because it means the motherboard part of this software hack is done!

In fact, we’ve already hacked the camera, as well, so we’re halfway there!

Hacking a camera into the extruder controller

Since the motherboard already does everything we need (passes along packets from the computer to the extruder controller), we only need to update the ArduinoSlaveExtruder code.

Building and uploading

If you followed the 4 links above, you’ll notice that they go to my own G3Firmware GitHub repository. You can download it yourself to play along by cloning the repository and checking out the ECv2.3rc0-camera branch.

To build the firmware and upload it to the extruder controller, we need some common development tools (make, in this case), and the Arduino development environment. With those things installed, we can compile everything by setting the ARDUINO_HOME environment variable to the path to our Arduino install’s java directory (e.g. on OS X this would be /Applications/Arduino.app/Contents/Resources/Java/), and simply run make.

Once the firmware has been compiled, we can upload it to the extruder controller by using the USB<->TTL cable that usually connects the motherboard to our computer. Plug the cable into the extruder controller, and run the make upload command. You’ll need to make sure that ARDUINO_HOME is set, and you will probably need to alter the Makefile to specify the correct serial port, and maybe to update the call to avrdude to include the path to the Arduino avrdude config file. You can see an example of that in this commit.

Once the firmware is uploaded to the extruder controller, the MakerBot is all set to take pictures!

… Of course, we still have no way to tell the MakerBot to take a picture, so stay tuned for that information in the next update: